Physics Nobel goes to exoplanet and cosmology pioneers

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Physics Nobel goes to exoplanet and cosmology pioneers

11.10.2019

Physics Nobel goes to exoplanet and cosmology pioneers

In 1995, Mayor, at the University of Geneva, Switzerland, and his then-student Queloz announced the first discovery of a planet orbiting a Sun-like star — launching a field that has become one of astronomy’s hottest. They detected the exoplanet through its tiny gravitational pull on its star, 51 Pegasi, a technique that is now used to study some of the more than 4,000 exoplanets known to exist.

Peebles, who is at Princeton University in New Jersey, developed a theoretical framework that the Nobel Committee says forms “the foundation of our modern understanding of the Universe’s history, from the Big Bang to the present day”.

Peebles helped to lay the theoretical foundations for the cosmic microwave background (CMB), the ‘afterglow’ of the Big Bang, and to establish the current ‘standard model’ of the evolution of the Universe. In this model, the mysterious substance known as dark matter plays a central part in assembling large-scale structures of the cosmos, such as galaxies and clusters of galaxies.

Mayor and Queloz, who are both Swiss and were born in 1942 and 1966, respectively, share one-half of the prize, worth 9 million Swedish kronor (US$910,000). Peebles, who was born in Winnipeg, Canada, in 1935, will receive the other half.

Surprise world

Mayor and Queloz’s discovery “started modern exoplanet science”, says Guillem Anglada-Escudé, an astronomer at the Institute for Space Sciences-CSIC in Barcelona, Spain.

Researchers had discovered exoplanets orbiting spinning cores of dead stars known as pulsars, but not around stars similar to our own, which could host habitable planets.

The pair’s discovery came as a surprise to the astronomy community. The planet they detected, called 51 Pegasi b, is a gas giant, a type that astronomers had expected would orbit the outer reaches of a solar system. But the pair found it orbiting around ten times closer to its star than Mercury is to the Sun — an early sign that other planetary systems might not be like our own.

Several groups were making similar observations at the time, but Mayor and Queloz were first to make the detection because they cast a wider net, says exoplanet astronomer Francesco Pepe. “When they started their programme at the Observatoire de Haute-Provence — by which they found 51 Pegasi b — they didn’t focus on trying to discover planets like those in our Solar System,” says Pepe, who is the head of the astronomy department at the University of Geneva. In particular, their observations enabled them to see Jupiter-sized planets with very tight orbits. “This made the difference.”